For the magnetospheric case, in analogy to CTTSs, we consider \({R_{\textnormal {acc}}}=5~R_{\mathrm {p}}\)  [1]},
but also \({R_{\textnormal {acc}}}=2~R_{\mathrm {p}}\)  for comparison, as the magnetic field may be weaker, whether in total or in its dipole component.
We assume that the flux coming from the postshock region (the accretion “hot spots”) passes tangentially through the accretion arc to the observer and thus travels a distance \({r_{\rm max}}\approx 1/3 \times \pi {R_{\textnormal {acc}}}/2 \approx {R_{\textnormal {acc}}}/2\) , as illustrated in Figure REF . Therefore, curvature can be ignored at the level of our approximation, and the radiative transfer can be performed also here purely radially.
